Managing heat in compact electronic enclosures is difficult because the aesthetic and performance demands from customers cause the enclosures to be form fit to the electronic components with little room for natural convection to dissipate heat. Usually, the integrated circuits (ICs) generating the largest amount of heat are located in the center of the enclosure and many customers object to vent openings in the enclosure directly above the printed circuit board (PCB). This causes the heat to be trapped in the enclosure and can damage sensitive components. Also, the outer surfaces of the enclosure can exceed temperature limits acceptable for a customer's touch.
Numerous approaches for managing heat exist. Some involve employing a plurality of vent openings and providing sufficient space in enclosures conducive to exhaust heat. However, many customers object to large enclosure sizes and excessive openings. Heatspreaders are commonly used in compact electronic enclosures to radiate heat into the walls of the enclosure but their dissipation of heat is limited. Finned heatsinks have been used in larger enclosures that allow movement of air through vents. In systems with finned heatsinks, there has to be enough room for air to circulate, and as such, this requirement generally causes the need for larger enclosures. Fans and blowers are used widely, but they generate noise that is objectionable to many customers. Fluid filled heat pipes have been used to transfer heat from the center of enclosures, but such an approach is expensive.
In most typical set top boxes, the PCB assemblies have components and connectors mounted on one side of the PCB in which there is an aesthetic motivation to form fit the enclosures to the components. This usually places one side of the enclosure close to the PCB and the other relatively farther away. This makes it useful to be able to draw heat in some directions through conduction and to shield radiation from the enclosure in others; however, this causes the need for the set top box to have additional height.
It is thus recognized that a further need exists to implement set top box designs which efficiently eliminate heat and which are compact, quiet, and cost effective.